selection_context.hpp

#ifndef LIBWTK_SDL2_SELECTION_CONTEXT_HPP
#define LIBWTK_SDL2_SELECTION_CONTEXT_HPP

#include <SDL2/SDL_rect.h>

#include "geometry.hpp"
#include "key_event.hpp"
enum class navigation_type;
struct widget;

// TODO work with shared_ptr (in case a selected widget gets removed)
//
// This class provides an optional mechanism to interact with the widgets. Think
// of it as traversing a 2-dimensional grid in which the widgets are positioned.
// The primary purpose is the use of a remote control.
//
// In principle this represents tabulator based widget focus.
struct selection_context
{
    selection_context(SDL_Rect widget_area, widget * w = nullptr);

    // Manually select a widget.
    void select_widget(widget * w);

    void unselect_widget();

    // Runs the selected widget's activation event (this may happen when
    // pressing the return key).
    void dispatch_activation();
    void dispatch_key_event(key_event const & ke);

    bool is_selected_widget(widget const * w) const;

    // Performs a selection action from the currently selected widgets position.
    // If no such widget exists, it will perform the action starting from the
    // given widget.
    //
    // This is the entry point of all navigation events.
    void navigate_selection(navigation_type nt, widget * main_widget);

    void change_widget_area(SDL_Rect new_box);

    private:

    void unselect_helper();
    void select_helper();

    point _selected_position;
    widget * _selected_widget;
    SDL_Rect _widget_area;
};

#endif